Process of manufacturing articles out of highly-refractory material.



. LBERT. PROCESS OF MANUFACTURING AR ICLES OUT OF HIGH CTORY MATERIAL. APPL A N FILED sum. :90 1,155,358.

Fay Z atented Oct. 5, 1915.

is practically fused.

TBIESCOTT M. HULIBERT, OF DETROIT, MICHIGAN.

specification of Letters Patent.

Application filed September 24, 1906. Serial No. 836,048.

To all whom it may concern:

Be it known that I, Pnnsoor'r M. HuLBnRT, a citizen of the United States of America, residing at e city of Detroit, in the county of Wayne and State of Michigan, have mvented certain new and useful Improvements in Processes of Manufacturing Articles Out of Highly-Refractory Material, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention relates to the manufacture of articles of highly refractory materials, such, for instance as silica, alumina, magnesia and other metallic oxids.

The invention consists in the novel method of integrating the material and of fashioning the same to the form desired, as hereinafter set forth. p

.The drawings illustrate a specific application of the method, namely, the manufac-. ture of a protected electrical heating unit.

Figures 1 to 5 illustrate the successive steps in the manufacture, and Fig.6 the manufactured article.

Broadly described, the method includes the following steps, first the molding of the desired shape from the finely comminuted refractory material; second, the heating of the molded article to a temperature at which integration takes place. This method differs from the usual methods of manufacturing pottery and porcelain wares first, in that no binding material is necessarily employed. The form is given and is retained throughout the process by the shape of the mold. Furthermore, the material may be homogeneous and the particles are brought together solely by pressure without the necessity of moistening. My improved process is further characterized by the method employed in baking or effecting the final integration of the material. This involves the heating of the mass to a temperature approximating the fusing point of the ma terial employed whereby theparticles are softened, and caused to adhere to each other without a binding substance. The integration' may be carried to any degreedesire'd from a point where a soft crumbling body is obtained to the point where the whole mass In the specific embodiment of my inven-.

Patented ea. 5; 1915.

non-oxidizable refractory material, such as I silica. Thus, the carbon which forms the heating resistance, and in operation is raised to a hlgh temperature, is inclosed and her-.

metically sealed, while the protecting body forms a medium for conducting the heat from the resistances and distributes it to the 'point desired. I

In order to secure a comparatively high resistance in a unit of small dimensions, I preferably form the carbon conductor of spiral shape. I also preferably employ graphitic carbon, and preferably the artificially prepared graphite, for the reason, first, that I have found this substance capable of being cut into spirals havinga small section of considerable length, and, second, for the reason that the graphite having been subjected to an extremely high temperature during the process of its manufacture will not change inform or composition by any subsequent heating to which it may be subjected.

As illustrated, Fig. 1 represents a rod,

of artificial graphite, which has been threaded for a portion of its length. This threading operation may be performed by any of the usual methods employed in threading metals. Fig. 2 represents the second step in the manufacture, in whichthe threaded rod A is inclosed in a sectional case, or jig, B closely fitting thethreads and holding the work to be further operated upon. The next operation also illustrated in Fig. 2 is the boring or cutting away of the center of the rod, so as to intersect the threads, and

sever the same to form a spiral. The third step in the operation is the filling of the cavity formed by boring with the refractory material, such as the finely comminuted silica. This may be done while the graphite spiral is still retained in the jig, and sufficient pressure is applied to compact the mass. In the next step of the'process, the spiral removed from the jig is placed within a mold '0, preferably formed of graphite, and is surrounded by a mass of the refractory material. This is suitably compacted by pressure or tamping, and surrounds the spiral as well as the terminals connected therewith. These terminals may be formed by separate rods of graphite D and E mechanically fitting the ends of the spiral A, and extending oppositely outward therefrom. The mold is also fashioned that the sihca covering will also surround these terminals and extend to near the ends thereof. The final step of the process is the heating of the molds to the required temperature,

temperature being approximately the formed in the bottom, as at G, an

fusing point of the refractory material and consequently very high. As it is practically impossible combustion, I preferably employ an electric furnace, such for instance as illustrated inis introduced by suitable means,

removable supporting it upon a vertically plug H. The cavity is heate by an arc sprung between carbon electrodes I introduced through the sides and near the upper portion of the chamber F. This will, develop within the chamber a very high tem perature, and the heat is distributedby re nalsD and E X silica case, p temperaturerequired In most of the arts.

. it is applicable to many time, the mold 'nace, and the article removed therefrom. I The effect from "integrate the flection from the walls, so'as to uniformly heat the mold 0 when placed therein. This mold being formed preferably of graphite will not itself be changed by heat.

After heating for the required length of is withdrawn from the furthe heating is to thoroughly silica, so that the graphite spiral is hermetically sealed and is thoroughly protected from oxidation. To complete the resistance, theends of the graphite termiareprovided with suitable connections by in an electric circuit. An electric current may then be passed through the spiral, and the heating effect may be carried. to any extent desired below th which latter is higher than the .While I have described one specific em bodiment of my invention, it is obvious that other uses.

take place during the integration process, I preferably employ contractible molds. As illustra e cavity within the mold C is tapered toward the top, and the bottom J of the mold is separate from the portion C, and supports the latter through themedium .of the mashrmkage will .terial within the cavity. Thus, as contracto obtain the required heat by which they may be included e fusing point of the oxidation the is also preferably formed of a separate piece,

which may lower to compensate for any contraction. This mold is preferably formed by fashioning the same from a solid block of artifically prepared graphite." The nature of this substance-is such that it may be easily cut, and at the same time it possesses a considerable degree ofrigidity, so that when once formed it will retain its shape. Moreover, this shape will not be changed even where heated to an excessively high temperature.

The refractory material, which is employed, is preferably finely comminuted. Thus it will take the form of the finest detail in the mold and during the integration process will shrink less thanwhere coarser material is used.-

What I claim as my invention is:

1. The method of forming articles of ticles of the contained material.

. 2. The method of forming articles of highly refractory materials which consists in compacting the comminuted material in a carbon mold corresponding to the final form of the article and heating said mold to produce integration by surface adhesion of the particles of the contained material.

3. The method of forming articles of highly refractory materials which consists in compacting the comminuted material in a fashioned mold of graphitic carbon corresponding to the final form of the article and 'in heating the mold to produce integration by surface adhesion of the particles of the contained body.

oxidizable electrical heat' resistances which consists in embedding said resistance In a body of comminuted non-oxidizable refractory material with enlarged terminals leading out from said body and in heating the body to integrate said refractory ma-. terial and hermeti y seal and protect from resistance therein.

5. The method of protecting carbon heating resistances which consists in embedding and completely protecting the same in a body of commmuted non-oxidizable refractory material and in heating to produce integration. of said refractory material.

6. The method of. forming electrical 1......

ing units' which consists in embeddings.

corresponding to thefinal form of the not combine with the contained ma graphite helix in a body of comminuted rein heating to produce integration of said fractory material, and in heating to produce material and the sealing in of said resistor. 10 integration of said material and the sealing In testimony whereof I affix my signature therein of said helix. in presence-of two Witnesses.

7. The method of forming electrical heat- PRESCOTT M. HULBERT. ing units which consists in embedding a tor- \Vitnesses: 4 tuously extending resistor of graphite in a JAMES P. BARRY,

body of comminuted refractory material and NELLIE KINSELLA. 

